[Python-Dev] PEP 433: Choose the default value of the new cloexec parameter

[Antoine Pitrou]

On Sun, 27 Jan 2013 12:23:15 +0100
Victor Stinner <victor.stinner at gmail.com> wrote:
> 2013/1/27 Guido van Rossum <guido at python.org>:
> > I had missed this detail. I agree that it should be exposed in the
> > interpreter. To my mind it is more like PYTHONPATH (which corresponds
> > roughly to sys.path manipulations) than like -R (which changes
> > something that should never be changed again, otherwise the sanity of
> > the interpreter be at risk). It would seem hard to unittest the
> > feature if it cannot be changed from within. But I can also think of
> > other use cases for changing it from within (e.g. a script that
> > decides on how to set it using a computation based on its arguments).
> 
> sys.path is usually only used to add a new path, not to remove path
> from other libraries. I'm not sure that it's the best example to
> compare it to sys.setdefaultcloexec().
> 
> If sys.setdefaultcloexec() accepts an argument (so allow
> sys.setdefaultcloexec(False)), problems happen when two libraries, or
> an application and a library, disagree. Depending how/when the library
> is loaded, the flag may be True or False.
> 
> I prefer to have a simple sys.setdefaultcloexec() which always set the
> flag to True. It's also simpler to explain how the default value is
> computed (it's less surprising).

I don't think such limitations are very useful in practice. Users
calling sys.setdefaultexec() will have to be sufficiently knowledgeable
to understand the implications, anyway.

Regards

Antoine.